Hi!I'm using a trasparent window in LoViewThumb to show image infos and it works pretty good on 24bit screens, on 16 bit screens under AmigaOS4.x the window was simply not trasparent, but on MOS 2.7 Hollywood crash and complain about alpha trasparent windows cant work...That was correct or was a bug? I ask it since on AmigaOS4.1 simply the window was not trasparent and all workls fine...

That's normal behaviour. On 16-bit screens there's obviously no room for any alpha channel information because you only have 5 bits red, 6 bits green and 5 bits of blue. By the way, please do not use the verb "crash" when Hollywood exits cleanly with an error message. That's not a crash, it's a clean exit because something went wrong. A crash means that Hollywood throws a system exception, freezes your system or leads to a reboot etc. Such crashes are always bugs. But if Hollywood just shows a requester complaining about something and then exits cleanly, then that's definitely not a crash but a predefined way of exiting to prevent a crash

Ok,not crash but clean exit, but however why that dont hanppen on AmigaOS4.1? Why simply Hollywood dont have the same (better) behaviour than on AmigaO4.1 also on MOS2.7 diaplaying a not trasparent window? OS limitaion?

It's implementation dependent. AFAIR OS4 has the alpha transparency feature implemented in its layers.library while on MorphOS it's dependent on the screen bitmap directly. That's why it's impossible to use alpha transparency on anything but 32-bit modes in MorphOS.

Hmmdi... I noticed now that MorphOS hangs when trying to run alpha transparent windows on 16bit screens. I haven't got logs yet, because almost everything freezes, even though mouse pointer moves, but can't do much anything else. I've tried several times with the AlphaApple example.